Q.

A block of mass m is placed on a surface having a vertical cross-section given by y=x2/4. If the coefficient of friction is 0.5, the maximum height above the ground at which the block can be placed without slipping is     [2024].

1 1/4 m  
2 1/2 m  
3 1/6 m  
4 1/3 m  

Ans.

(1)

fs=mgsinθ                    ...(1)

N=mgcosθ                  ...(2)

Now, fs≤μN

mgsinθ≤μmgcosθ

tanθ≤μ                         ...(3)

According to question, y=x24

tanθ=dydx=14·2x=x2

Put in (3) x2≤μ⇒x≤2(0.5)

⇒x≤1 So y≤124⇒ymax=14=0.25